This invention relates to a computer-implemented method and computer-based apparatus for adaptive control via a matrix of feed-forward relationships respective to a process or series of processes implemented in an apparatus such as a chemical manufacturing plant.
Optimized operation of manufacturing systems is valued for providing benefits in profitability, productivity, environmental impact, and high product quality. The increasing capability of low cost computers to deliver resolution of complex control approaches has advanced optimized operation to incorporate techniques which could not have been economically explored even a few years ago. One of the techniques enabled at a relatively early stage of computer use in control was Dynamic Matrix Control, a form of feed-forward control based upon a method where outputs, or controlled variables, are predicted to move in the context of known control settings and current data. Feed-forward methodologies are, in many cases, superior to feedback methodologies which wait until process disturbances have actually changed the controlled variables before controller action is taken. Indeed, an ideal controller provides both feed-forward and feedback action in sufficient capability to achieve optimal operation.
Dynamic Matrix Control is discussed in U.S. Pat. No. 4,349,869 for a DYNAMIC MATRIX CONTROL METHOD which issued on Sep. 14, 1982 to David M. Prett, Brian L. Ramaker, and Charles R. Cutler. This patent is incorporated herein by reference. Dynamic Matrix Control has helped in solving control issues related to limitations in future controller response in the context of a decision at a particular time, accommodation of the full set of conditions in a system being controlled, complexity in multiple influences, and non-linear impacts respective to disturbance.
But, in its classic form, Dynamic Matrix Control (DMC) also has presented challenges in dealing with process stability during transients or at different turndowns or deviations from the fluid flow throughput used in model definition and tuning. The need for stability in use of DMC in all operational contexts has been a driving force in the development of the present invention, which provides beneficial features in stability, robustness, and adaptability to substantially enhance the traditional DMC approach.
The invention provides a method for computer-implemented controlling of a processing apparatus having at least one independently controlled manipulated variable and at least one controlled variable responsive to the manipulated variable, comprising the steps of:
defining an expected variation in magnitude for each controlled variable as a respective function of each manipulated variable from a set of at least two models, the model set having a dynamic response inertial characteristic; and
implementing a change defined from the model set to modify the manipulated variable in the processing apparatus.